This project is an investigation of whether microdeletions in the pseudoautosomal regions of X and Y chromosones account for a significant proportion of idiopathic or familial short stature in children. This study involves the application of the molecular technique polymerase chain reaction and the molecular cytogenetic technique fluorescense in situ hybridization. Blood samples are being collected from 50 patients (healthy short children 5-15 years) and 50 controls. Compensation in the form of ten dollars is given to each patient at the time of the blood draw.